Play Video
1
Antenna-Theory.com Presents the Spiral Antenna
Antenna-Theory.com Presents the Spiral Antenna
::2011/07/17::
Play Video
2
Spiral antenna
Spiral antenna
::2012/05/23::
Play Video
3
Cavity backed log spiral antenna
Cavity backed log spiral antenna
::2013/03/11::
Play Video
4
FPVStyle com   Aomway 11Db Helical Antenna
FPVStyle com Aomway 11Db Helical Antenna
::2014/08/20::
Play Video
5
K6ZRH- TAK-tenna antenna demo (20M shortest HF dipole spiral antenna)
K6ZRH- TAK-tenna antenna demo (20M shortest HF dipole spiral antenna)
::2009/08/25::
Play Video
6
What is a Helical Antenna?
What is a Helical Antenna?
::2014/06/21::
Play Video
7
FPV 5.8GHz helical antenna shootout
FPV 5.8GHz helical antenna shootout
::2014/05/02::
Play Video
8
Two 5.8GHz FPV helical antennas compared
Two 5.8GHz FPV helical antennas compared
::2014/02/06::
Play Video
9
Spiral Antenna Video 3
Spiral Antenna Video 3
::2012/03/28::
Play Video
10
Build a 3 turn Helical antenna for 5.8ghz
Build a 3 turn Helical antenna for 5.8ghz
::2012/07/04::
Play Video
11
CST MWS Tutorial 02: Geometrical Design of a Helix Antenna
CST MWS Tutorial 02: Geometrical Design of a Helix Antenna
::2011/07/06::
Play Video
12
Mini Helical Antenna 2.4GHz
Mini Helical Antenna 2.4GHz
::2013/04/06::
Play Video
13
AM Spiral Loop Antenna
AM Spiral Loop Antenna
::2010/03/16::
Play Video
14
An Innovative Semicircular Spiral Antenna for On Metal Passive RFID Applications
An Innovative Semicircular Spiral Antenna for On Metal Passive RFID Applications
::2013/07/08::
Play Video
15
Helical Antenna 5.8GHz 10 Turn
Helical Antenna 5.8GHz 10 Turn
::2013/11/08::
Play Video
16
How to build a 5.8 GHz 4 Turn Helical Part 1
How to build a 5.8 GHz 4 Turn Helical Part 1
::2013/01/23::
Play Video
17
Kc boro marble spiral antenna pink swirls
Kc boro marble spiral antenna pink swirls
::2010/12/20::
Play Video
18
6/02/2014 -- Spiral Vortex RADAR pulse in Australia - covering Exmouth Antenna Array
6/02/2014 -- Spiral Vortex RADAR pulse in Australia - covering Exmouth Antenna Array
::2014/06/02::
Play Video
19
Electric field around axial mode helical antenna
Electric field around axial mode helical antenna
::2011/11/10::
Play Video
20
2.4 Ghz Helical Antenna -Part two
2.4 Ghz Helical Antenna -Part two
::2011/02/18::
Play Video
21
iBcrazy Helical & Crosshair Antennas for FPV
iBcrazy Helical & Crosshair Antennas for FPV
::2013/03/22::
Play Video
22
5.8GHz CP Helical antenna.
5.8GHz CP Helical antenna.
::2012/01/14::
Play Video
23
2.4 Ghz Helical Antenna -Part one
2.4 Ghz Helical Antenna -Part one
::2011/02/18::
Play Video
24
HK EPP FPV test of Helical antenna 1
HK EPP FPV test of Helical antenna 1
::2012/09/04::
Play Video
25
Mini wing fpv flight and Helical antenna test
Mini wing fpv flight and Helical antenna test
::2013/05/15::
Play Video
26
HF Spiral Loop Antenna video 2.
HF Spiral Loop Antenna video 2.
::2012/03/26::
Play Video
27
Antena Helice en CST Studio
Antena Helice en CST Studio
::2013/03/08::
Play Video
28
Introduction to FPV - Antenna choices (dipole, circular, helical and patch)
Introduction to FPV - Antenna choices (dipole, circular, helical and patch)
::2014/07/03::
Play Video
29
DJI Phantom + DJI Zenmuse H3-2D Gimbal + go pro 3+ black + fatshark fpv with spiral antenna
DJI Phantom + DJI Zenmuse H3-2D Gimbal + go pro 3+ black + fatshark fpv with spiral antenna
::2013/11/16::
Play Video
30
3-Square Antenna for Wi-Fi Band
3-Square Antenna for Wi-Fi Band
::2010/11/30::
Play Video
31
Magnetic loop antenna helical loop antenna 2 element
Magnetic loop antenna helical loop antenna 2 element
::2011/12/30::
Play Video
32
Antenna and Propagation - Polarization Measurement (Lab 5)
Antenna and Propagation - Polarization Measurement (Lab 5)
::2013/05/13::
Play Video
33
Modern Academy for engineering (Spiral)
Modern Academy for engineering (Spiral)
::2008/07/18::
Play Video
34
AM Broadcast Band Tunable Loop Antenna
AM Broadcast Band Tunable Loop Antenna
::2013/12/17::
Play Video
35
1st EVER? 5.8GHz RED ANTZ 4x 12 TURN HELICAL HELIX ANTENNA ARRAY BUILD n3m1s1s
1st EVER? 5.8GHz RED ANTZ 4x 12 TURN HELICAL HELIX ANTENNA ARRAY BUILD n3m1s1s
::2012/06/21::
Play Video
36
Magnetic loop antenna Dx Contacts Helical Loop Antenna
Magnetic loop antenna Dx Contacts Helical Loop Antenna
::2012/05/06::
Play Video
37
Len Horowitz - DNA: Pirates of the Sacred Spiral [FULL]
Len Horowitz - DNA: Pirates of the Sacred Spiral [FULL]
::2013/09/01::
Play Video
38
BEST VIDEO of spiral light over Norway
BEST VIDEO of spiral light over Norway
::2009/12/11::
Play Video
39
Phantom 2 First Flight in Bishan Park
Phantom 2 First Flight in Bishan Park
::2014/01/07::
Play Video
40
G3XBM
G3XBM's 500kHz antenna (in snow)
::2009/12/18::
Play Video
41
Bashar Explains How the Free Energy Space-Time Antenna Works
Bashar Explains How the Free Energy Space-Time Antenna Works
::2011/03/17::
Play Video
42
HOBBYKING BIXLER 2, HELICAL & CLOVER LEAF ANTENNA TEST, 5.8 GHZ, CYCLOPS NOVA OSD, SONY CAM 600 TVL
HOBBYKING BIXLER 2, HELICAL & CLOVER LEAF ANTENNA TEST, 5.8 GHZ, CYCLOPS NOVA OSD, SONY CAM 600 TVL
::2012/11/20::
Play Video
43
◘ Halloween Headband ◘ Batty Antenna Bouncers ◘
◘ Halloween Headband ◘ Batty Antenna Bouncers ◘
::2013/10/15::
Play Video
44
Q-par Angus - Innovative Microwave Antennas Engineering
Q-par Angus - Innovative Microwave Antennas Engineering
::2012/03/14::
Play Video
45
16 TAK anTENNA Radial Current in Capacytor Correnti radiali in Condensatore
16 TAK anTENNA Radial Current in Capacytor Correnti radiali in Condensatore
::2009/12/22::
Play Video
46
Rainbow Loom Advanced 3d Snail Charm - Spiral Mushroom
Rainbow Loom Advanced 3d Snail Charm - Spiral Mushroom
::2014/05/08::
Play Video
47
DJI Phantom 2 Vision Wifi Range Extender / Repeater  External Antenna Mod increase FPV range.
DJI Phantom 2 Vision Wifi Range Extender / Repeater External Antenna Mod increase FPV range.
::2014/01/11::
Play Video
48
Flite Test - Cloverleaf Antenna - FLITE TIP
Flite Test - Cloverleaf Antenna - FLITE TIP
::2012/11/12::
Play Video
49
EMP Jammer Telecomando 2014 Generator  Multifrequency Anti-Defender Lithium batteries RikisShop
EMP Jammer Telecomando 2014 Generator Multifrequency Anti-Defender Lithium batteries RikisShop
::2013/11/23::
Play Video
50
4.1 Antenna Basics
4.1 Antenna Basics
::2013/04/15::
NEXT >>
RESULTS [51 .. 101]
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Two-arm log spiral antenna
Not to be confused with helical antenna.

In microwave systems, a spiral antenna is a type of RF antenna. It is shaped as a two-arm spiral, or more arms may be used.[1] Spiral antennas were first described in 1956.[2] Spiral antennas belong to the class of frequency independent antennas which operate over a wide range of frequencies. Polarization, radiation pattern and impedance of such antennas remain unchanged over large bandwidth.[3] Such antennas are inherently circularly polarized with low gain. Array of spiral antennas can be used to increase the gain. Spiral antennas are reduced size antennas with its windings making it an extremely small structure. Lossy cavities are usually placed at the back to eliminate back lobes because a unidirectional pattern is usually preferred in such antennas. Spiral antennas are classified into different types; archimedean spiral, square spiral and star spiral etc. Archimedean spiral is the most popular configuration.

Working[edit]

These antennas operate in 3W way; traveling wave, fast wave and leaky wave. The traveling wave, formed on spiral arms, allows for broadband performance, fast wave due to mutual coupling phenomenon occurring between arms of spiral and leaky wave leaks the energy during propagation through the spiral arms to produce radiation. Ring theory (band theory) explains the working principle of spiral antenna. The theory states that spiral antenna radiates from a region called active region where the circumference of spiral equals wavelength.[4]

Design[edit]

Different design parameters are to be considered while designing a square spiral antenna. The parameters include spacing between the turns s, width of arm w, inner radius r_1 and outer radius r_2. The inner radius is measured from center of the spiral to center of the first turn while the outer radius is measured from center of the spiral to center of the outermost turn. Other than these design parameters, spiral antennas have lowest (f_{\text{low}} = c/2 \pi r_2) and highest (f_{\text{high}} = c/2 \pi r_1) operating frequencies. Here c corresponds to speed of light. In an (r,\theta) coordinate system, the spiral grows along the r-axis and \theta-axis simultaneously. All spirals satisfy r = a + b\theta equation where a corresponds to growth factor and b corresponds to multiplication factor.

Different designs of spiral antenna can be obtained by varying number of turns it contains, the spacing between its turns and the width of its arm. A dielectric medium is used with a specific permittivity and dimensions over which the spiral is printed. Dielectric mediums like Rogers RT Duroid help in reducing the physical size of antenna. Thin substrates with higher permittivity can achieve the same result as thick substrates with lower permittivity. The only problem with such materials is their less availability and high costs.[5]

Applications[edit]

A spiral antenna transmits EM waves having a circular polarization. It will receive linearly polarized EM waves in any orientation, but will attenuate signals received with the opposite circular polarization. A spiral antenna will reject circularly polarized waves of one type, while receiving perfectly well waves having the other polarization.

One application of spiral antennas is wideband communications. Another application of spiral antennas is monitoring of the frequency spectrum. One antenna can receive over a wide bandwidth, for example a ratio 5:1 between the maximum and minimum frequency. Usually a pair of spiral antennas are used in this application, having identical parameters except the polarization, which is opposite (one is right-hand, the other left-hand oriented). Spiral antennas are useful for microwave direction-finding.[6]

Elements[edit]

The antenna includes two conductive spirals or arms, extending from the center outwards. The antenna may be a flat disc, with conductors resembling a pair of loosely-nested clock springs, or the spirals may extend in a three-dimensional shape like a screw thread. The direction of rotation of the spiral defines the direction of antenna polarization. Additional spirals may be included as well, to form a multi-spiral structure. Usually the spiral is cavity-backed, that is there is a cavity of air or non-conductive material or vacuum, surrounded by conductive walls; the cavity changes the antenna pattern to a unidirectional shape. The output of the antenna is a balanced line. If one input or output line is desired, for example a coaxial line, then a balun or other device is added to so transform the signals.

References[edit]

  1. ^ Richard C. Johnson, Henry Jasik, Antenna Engineering Handbook, Second Edition, ISBN 0-07-032291-0, 1961, Chapter 14-2
  2. ^ Orr, William I. (1976). Beam Antenna Handbook, 5th Edition. Radio Publications, Inc. pp. 185–186. 
  3. ^ Paul E. Mayes, “Frequency-Independent Antennas and Broad-Band Derivatives Thereof”, Proceedings of the IEEE, Volume: 80 , Issue: 1, Digital Object Identifier: 10.1109/5.119570, Publication Year: 1992, Page(s): 103 - 112
  4. ^ A. Mehta, D. Mirshekar-Syahkal and H. Nakano , “Beam adaptive single arm rectangular spiral antenna with switches”, Microwaves, Antennas and Propagation, IEE Proceedings - Volume: 153 , Issue: 1, Digital Object Identifier: 10.1049/ip-map:20050045, Publication Year: 2006 , Page(s): 13 – 18
  5. ^ Asad, M., Gilani, J., Khalid, A. and Iqbal, M.S., “Optimizing Q factor of square spiral antenna ”, PACCS 2010, Page(s): 227 - 230
  6. ^ Stephen E. Lipsky "Microwave Passive Direction Finding " SciTech Publishing, 2004 ISBN 1-891121-23-5 page 40

"Practical antenna" references[edit]

Wikipedia content is licensed under the GFDL License
Powered by YouTube
LEGAL
  • Mashpedia © 2014